llvm dev - Dec 2018 - Migrate utils/ Python 2 scripts to Python 3

Sadly, neither the latest version of RedHat (released in 2014), nor the
latest version of macOS (released in 2017) have any version of python3
available with the default system. On the other hand, TTBOMK, every system
that does have python3 available also makes python2.7 also easily available.

LLVM is not a primarily python project, so keeping up with the latest
features of the language, and making them available for developers of LLVM
is not terribly interesting (contrast with C++ -- enabling developers of
LLVM to use new C++ features does have a lot of value). There's also no
particular reason to think that developers will have already installed the
latest version of python on their systems, if it takes effort to do so.

Python is used here as a convenient scripting language primarily because it
is commonly/conveniently available across platforms. Requiring a python
version which does not have the widespread availability (and without a
compelling reason to want the higher version, other than that it's newer)
does not seem to make much sense.

So, ISTM that unfortunately, the decision to require python3 for is still
premature, even some 10 years after its initial release. (Whether that
state of the world is ridiculous, or whose fault that is, is irrelevant
here; anyone who wants to have that discussion can go have it on python-dev
for the 20000th time.)

That said, I do think it could make sense to prepare llvm for the world in
which "python" is python3 on some systems. So, I'd propose the
following:
1. Change all #! lines to say "#!/usr/bin/env python2.7" instead of
"#!/usr/bin/env python", if they only work with 2.7.
2. If someone feels motivated, and if it doesn't make the code obtuse, port
scripts to work with either version -- and for such scripts, change the #!
line to say "#!/usr/bin/env python".


On Thu, Feb 1, 2018 at 3:05 AM, Dimitry Andric via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> You might want to tell that to the Prominent North American Enterprise
> Linux Vendor that everybody is using... :)
>
> -Dimitry
>
> > On 1 Feb 2018, at 06:28, Tim Northover via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > Since we seem to be voting, I'll -1 it. It's pretty ridiculous
to have
> > a system without Python 3 in 2018 and anyone supplying such a
> > monstrosity should be encouraged to stop it.
> >
> > Tim.
> >
> > On 1 February 2018 at 05:20, Philip Reames via llvm-dev
> > <llvm-dev at lists.llvm.org> wrote:
> >> +1 to what Chris and Justin said.
> >>
> >> I see no strong benefit to moving to python3 and substantial
costs.
> >>
> >> Philip
> >>
> >>
> >> On 01/30/2018 11:20 AM, Chris Matthews via llvm-dev wrote:
> >>
> >> Personally, every machine I work with only has Python 2.7.
> >>
> >> Justin is correct that there is a non-trivial amount of effort to
> convert
> >> the bots.
> >>
> >> Python 3 is wonderful. But, a Python 3 dependency seems like one
burden
> that
> >> could be avoided.  We have already made that trade-off in the
past, for
> >> example by only using standard python packages, so there is
> less/nothing to
> >> pip install when getting started.  Dependencies likes host
compiler and
> >> cmake totally make sense given they are central to how LLVM is
made.  I
> >> don’t think the same for the python code.
> >>
> >> I’m in favor of 2/3 compatibility until the death clock ends.
> >>
> >> On Jan 30, 2018, at 4:48 AM, 陳韋任 via llvm-dev <llvm-dev at
lists.llvm.org>
> >> wrote:
> >>
> >> Does Python 3 have feature we want to use in LLVM codebase, and no
> >> workaround there? If so, please give some examples. I think that
makes
> the
> >> discussion more concrete.
> >>
> >> 2018-01-30 4:46 GMT+08:00 Fāng-ruì Sòng via llvm-dev
> >> <llvm-dev at lists.llvm.org>:
> >>>
> >>> Hi LLVM-Devs,
> >>>
> >>> I noticed that many Python scripts under utils/ have a shebang
of
> >>> `#!/usr/bin/python` (which is a symlink to python2.7 on many
platforms)
> >>> and some of them use Python 2 syntax that is not compatible
with
> Python 3
> >>> (e.g. print statements; str/bytes)
> >>>
> >>> I created a revision to migrate
utils/update_{llc_,}_test_checks.py
> from
> >>> Python 2 to Python 3 https://reviews.llvm.org/D42450 , the
arguments
> against
> >>> making it Python 3 is:
> >>>
> >>> * There are many Mac OS X users and Mac OS X 10.8 comes with
Python 2.7
> >>> pre-installed [0] but not Python 3.
> >>> * Forcing scripts to use Python 3 (by doing so we can avoid
some
> >>> compatibility trouble) may not be a good idea.
> >>>
> >>> Python 2.7 was published in 2010 and planned as the last of
the 2.x
> >>> releases. It will not be maintained past 2020 and there is
also a
> retirement
> >>> page https://pythonclock.org/ .
> >>>
> >>> The second argument would not need to be addressed if the
first one did
> >>> not lay too much burden on developers. After all, we have to
install
> `cmake,
> >>> ninja/GNU Make / libedit(for lldb)` to build LLVM. These
packages are
> not
> >>> installed by default on many platforms.
> >>>
> >>> Thoughts on deprecating Python 2 for utils/ scripts (different
from
> >>> libclang or lldb scripts) which are not user-facing?
> >>>
> >>> [0]:
> >>> https://docs.python.org/3/using/mac.html#getting-and-
> installing-macpython
> >>>
> >>>
> >>> Thanks,
> >>> Fangrui
> >>> _______________________________________________
> >>> LLVM Developers mailing list
> >>> llvm-dev at lists.llvm.org
> >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >>
> >>
> >>
> >>
> >> --
> >> Wei-Ren Chen (陳韋任)
> >> Homepage: https://people.cs.nctu.edu.tw/~chenwj
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >>
> >>
> >>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >>
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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As mentioned in https://docs.python.org/3/using/unix.html#miscellaneous, for
Python 3 the shebang line should be:

#!/usr/bin/env python3

For Python 2 the shebang line should probably be:

#!/usr/bin/env python2

but as Python 3 should never install its executable under the name
"python", you could also let it stay at:

#!/usr/bin/env python

instead.

-Dimitry
> On 1 Feb 2018, at 22:47, James Y Knight <jyknight at google.com>
wrote:
> 
> Sadly, neither the latest version of RedHat (released in 2014), nor the
latest version of macOS (released in 2017) have any version of python3 available
with the default system. On the other hand, TTBOMK, every system that does have
python3 available also makes python2.7 also easily available.
> 
> LLVM is not a primarily python project, so keeping up with the latest
features of the language, and making them available for developers of LLVM is
not terribly interesting (contrast with C++ -- enabling developers of LLVM to
use new C++ features does have a lot of value). There's also no particular
reason to think that developers will have already installed the latest version
of python on their systems, if it takes effort to do so.
> 
> Python is used here as a convenient scripting language primarily because it
is commonly/conveniently available across platforms. Requiring a python version
which does not have the widespread availability (and without a compelling reason
to want the higher version, other than that it's newer) does not seem to
make much sense.
> 
> So, ISTM that unfortunately, the decision to require python3 for is still
premature, even some 10 years after its initial release. (Whether that state of
the world is ridiculous, or whose fault that is, is irrelevant here; anyone who
wants to have that discussion can go have it on python-dev for the 20000th
time.)
> 
> That said, I do think it could make sense to prepare llvm for the world in
which "python" is python3 on some systems. So, I'd propose the
following:
> 1. Change all #! lines to say "#!/usr/bin/env python2.7" instead
of "#!/usr/bin/env python", if they only work with 2.7.
> 2. If someone feels motivated, and if it doesn't make the code obtuse,
port scripts to work with either version -- and for such scripts, change the #!
line to say "#!/usr/bin/env python".
> 
> 
> On Thu, Feb 1, 2018 at 3:05 AM, Dimitry Andric via llvm-dev <llvm-dev at
lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> You might want to tell that to the Prominent North American Enterprise
Linux Vendor that everybody is using... :)
> 
> -Dimitry
> 
> > On 1 Feb 2018, at 06:28, Tim Northover via llvm-dev <llvm-dev at
lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> >
> > Since we seem to be voting, I'll -1 it. It's pretty ridiculous
to have
> > a system without Python 3 in 2018 and anyone supplying such a
> > monstrosity should be encouraged to stop it.
> >
> > Tim.
> >
> > On 1 February 2018 at 05:20, Philip Reames via llvm-dev
> > <llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>> wrote:
> >> +1 to what Chris and Justin said.
> >>
> >> I see no strong benefit to moving to python3 and substantial
costs.
> >>
> >> Philip
> >>
> >>
> >> On 01/30/2018 11:20 AM, Chris Matthews via llvm-dev wrote:
> >>
> >> Personally, every machine I work with only has Python 2.7.
> >>
> >> Justin is correct that there is a non-trivial amount of effort to
convert
> >> the bots.
> >>
> >> Python 3 is wonderful. But, a Python 3 dependency seems like one
burden that
> >> could be avoided.  We have already made that trade-off in the
past, for
> >> example by only using standard python packages, so there is
less/nothing to
> >> pip install when getting started.  Dependencies likes host
compiler and
> >> cmake totally make sense given they are central to how LLVM is
made.  I
> >> don’t think the same for the python code.
> >>
> >> I’m in favor of 2/3 compatibility until the death clock ends.
> >>
> >> On Jan 30, 2018, at 4:48 AM, 陳韋任 via llvm-dev <llvm-dev at
lists.llvm.org <mailto:llvm-dev at lists.llvm.org>>
> >> wrote:
> >>
> >> Does Python 3 have feature we want to use in LLVM codebase, and no
> >> workaround there? If so, please give some examples. I think that
makes the
> >> discussion more concrete.
> >>
> >> 2018-01-30 4:46 GMT+08:00 Fāng-ruì Sòng via llvm-dev
> >> <llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>>:
> >>>
> >>> Hi LLVM-Devs,
> >>>
> >>> I noticed that many Python scripts under utils/ have a shebang
of
> >>> `#!/usr/bin/python` (which is a symlink to python2.7 on many
platforms)
> >>> and some of them use Python 2 syntax that is not compatible
with Python 3
> >>> (e.g. print statements; str/bytes)
> >>>
> >>> I created a revision to migrate
utils/update_{llc_,}_test_checks.py from
> >>> Python 2 to Python 3 https://reviews.llvm.org/D42450
<https://reviews.llvm.org/D42450> , the arguments against
> >>> making it Python 3 is:
> >>>
> >>> * There are many Mac OS X users and Mac OS X 10.8 comes with
Python 2.7
> >>> pre-installed [0] but not Python 3.
> >>> * Forcing scripts to use Python 3 (by doing so we can avoid
some
> >>> compatibility trouble) may not be a good idea.
> >>>
> >>> Python 2.7 was published in 2010 and planned as the last of
the 2.x
> >>> releases. It will not be maintained past 2020 and there is
also a retirement
> >>> page https://pythonclock.org/ <https://pythonclock.org/>
.
> >>>
> >>> The second argument would not need to be addressed if the
first one did
> >>> not lay too much burden on developers. After all, we have to
install `cmake,
> >>> ninja/GNU Make / libedit(for lldb)` to build LLVM. These
packages are not
> >>> installed by default on many platforms.
> >>>
> >>> Thoughts on deprecating Python 2 for utils/ scripts (different
from
> >>> libclang or lldb scripts) which are not user-facing?
> >>>
> >>> [0]:
> >>>
https://docs.python.org/3/using/mac.html#getting-and-installing-macpython
<https://docs.python.org/3/using/mac.html#getting-and-installing-macpython>
> >>>
> >>>
> >>> Thanks,
> >>> Fangrui
> >>> _______________________________________________
> >>> LLVM Developers mailing list
> >>> llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>
> >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> >>
> >>
> >>
> >>
> >> --
> >> Wei-Ren Chen (陳韋任)
> >> Homepage: https://people.cs.nctu.edu.tw/~chenwj
<https://people.cs.nctu.edu.tw/~chenwj>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> >>
> >>
> >>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> >>
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> 
> 
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> On Feb 1, 2018, at 1:59 PM, Dimitry Andric via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> As mentioned in https://docs.python.org/3/using/unix.html#miscellaneous
<https://docs.python.org/3/using/unix.html#miscellaneous>, for Python 3
the shebang line should be:
> 
> #!/usr/bin/env python3
> 
> For Python 2 the shebang line should probably be:
> 
> #!/usr/bin/env python2
> 
Unfortunately macOS never shipped with this symlink AFAIK. so `python2.7` should
work better for a bigger number of macOS users.

- Matthias
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Nope.

Regarding "python" potentially pointing to python3:

Arch Linux has done that for years. That unilateral decision on their part
was widely-decried as a mistake at the time, and spawned the python doc you
reference saying that shouldn't be done. However, Fedora is now making
noises about doing the same, in a few years, after driving a change in the
upstream recommendation. While it's certainly not finalized, I'd fully
expect this to happen at some point.

https://fedoraproject.org/wiki/FinalizingFedoraSwitchtoPython3
https://wiki.archlinux.org/index.php/python

And, regarding using "python2" instead of "python2.7":

Since python2.7 is the last-ever python2 version, and also the minimum
version required by llvm, the name "python2" is false generality.
Additionally, the "python2" symlink is missing on _many_ systems (not
just
macos). So, the choice of "python2.7" is clearly the better option
here.


On Feb 1, 2018 4:59 PM, "Dimitry Andric" <dimitry at andric.com>
wrote:

As mentioned in https://docs.python.org/3/using/unix.html#miscellaneous,
for Python 3 the shebang line should be:

#!/usr/bin/env python3

For Python 2 the shebang line should probably be:

#!/usr/bin/env python2

but as Python 3 should never install its executable under the name
"python", you could also let it stay at:

#!/usr/bin/env python

instead.

-Dimitry

On 1 Feb 2018, at 22:47, James Y Knight <jyknight at google.com> wrote:

Sadly, neither the latest version of RedHat (released in 2014), nor the
latest version of macOS (released in 2017) have any version of python3
available with the default system. On the other hand, TTBOMK, every system
that does have python3 available also makes python2.7 also easily available.

LLVM is not a primarily python project, so keeping up with the latest
features of the language, and making them available for developers of LLVM
is not terribly interesting (contrast with C++ -- enabling developers of
LLVM to use new C++ features does have a lot of value). There's also no
particular reason to think that developers will have already installed the
latest version of python on their systems, if it takes effort to do so.

Python is used here as a convenient scripting language primarily because it
is commonly/conveniently available across platforms. Requiring a python
version which does not have the widespread availability (and without a
compelling reason to want the higher version, other than that it's newer)
does not seem to make much sense.

So, ISTM that unfortunately, the decision to require python3 for is still
premature, even some 10 years after its initial release. (Whether that
state of the world is ridiculous, or whose fault that is, is irrelevant
here; anyone who wants to have that discussion can go have it on python-dev
for the 20000th time.)

That said, I do think it could make sense to prepare llvm for the world in
which "python" is python3 on some systems. So, I'd propose the
following:
1. Change all #! lines to say "#!/usr/bin/env python2.7" instead of
"#!/usr/bin/env python", if they only work with 2.7.
2. If someone feels motivated, and if it doesn't make the code obtuse, port
scripts to work with either version -- and for such scripts, change the #!
line to say "#!/usr/bin/env python".


On Thu, Feb 1, 2018 at 3:05 AM, Dimitry Andric via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> You might want to tell that to the Prominent North American Enterprise
> Linux Vendor that everybody is using... :)
>
> -Dimitry
>
> > On 1 Feb 2018, at 06:28, Tim Northover via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > Since we seem to be voting, I'll -1 it. It's pretty ridiculous
to have
> > a system without Python 3 in 2018 and anyone supplying such a
> > monstrosity should be encouraged to stop it.
> >
> > Tim.
> >
> > On 1 February 2018 at 05:20, Philip Reames via llvm-dev
> > <llvm-dev at lists.llvm.org> wrote:
> >> +1 to what Chris and Justin said.
> >>
> >> I see no strong benefit to moving to python3 and substantial
costs.
> >>
> >> Philip
> >>
> >>
> >> On 01/30/2018 11:20 AM, Chris Matthews via llvm-dev wrote:
> >>
> >> Personally, every machine I work with only has Python 2.7.
> >>
> >> Justin is correct that there is a non-trivial amount of effort to
> convert
> >> the bots.
> >>
> >> Python 3 is wonderful. But, a Python 3 dependency seems like one
burden
> that
> >> could be avoided.  We have already made that trade-off in the
past, for
> >> example by only using standard python packages, so there is
> less/nothing to
> >> pip install when getting started.  Dependencies likes host
compiler and
> >> cmake totally make sense given they are central to how LLVM is
made.  I
> >> don’t think the same for the python code.
> >>
> >> I’m in favor of 2/3 compatibility until the death clock ends.
> >>
> >> On Jan 30, 2018, at 4:48 AM, 陳韋任 via llvm-dev <llvm-dev at
lists.llvm.org>
> >> wrote:
> >>
> >> Does Python 3 have feature we want to use in LLVM codebase, and no
> >> workaround there? If so, please give some examples. I think that
makes
> the
> >> discussion more concrete.
> >>
> >> 2018-01-30 4:46 GMT+08:00 Fāng-ruì Sòng via llvm-dev
> >> <llvm-dev at lists.llvm.org>:
> >>>
> >>> Hi LLVM-Devs,
> >>>
> >>> I noticed that many Python scripts under utils/ have a shebang
of
> >>> `#!/usr/bin/python` (which is a symlink to python2.7 on many
platforms)
> >>> and some of them use Python 2 syntax that is not compatible
with
> Python 3
> >>> (e.g. print statements; str/bytes)
> >>>
> >>> I created a revision to migrate
utils/update_{llc_,}_test_checks.py
> from
> >>> Python 2 to Python 3 https://reviews.llvm.org/D42450 , the
arguments
> against
> >>> making it Python 3 is:
> >>>
> >>> * There are many Mac OS X users and Mac OS X 10.8 comes with
Python 2.7
> >>> pre-installed [0] but not Python 3.
> >>> * Forcing scripts to use Python 3 (by doing so we can avoid
some
> >>> compatibility trouble) may not be a good idea.
> >>>
> >>> Python 2.7 was published in 2010 and planned as the last of
the 2.x
> >>> releases. It will not be maintained past 2020 and there is
also a
> retirement
> >>> page https://pythonclock.org/ .
> >>>
> >>> The second argument would not need to be addressed if the
first one did
> >>> not lay too much burden on developers. After all, we have to
install
> `cmake,
> >>> ninja/GNU Make / libedit(for lldb)` to build LLVM. These
packages are
> not
> >>> installed by default on many platforms.
> >>>
> >>> Thoughts on deprecating Python 2 for utils/ scripts (different
from
> >>> libclang or lldb scripts) which are not user-facing?
> >>>
> >>> [0]:
> >>> https://docs.python.org/3/using/mac.html#getting-and-install
> ing-macpython
> >>>
> >>>
> >>> Thanks,
> >>> Fangrui
> >>> _______________________________________________
> >>> LLVM Developers mailing list
> >>> llvm-dev at lists.llvm.org
> >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >>
> >>
> >>
> >>
> >> --
> >> Wei-Ren Chen (陳韋任)
> >> Homepage: https://people.cs.nctu.edu.tw/~chenwj
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >>
> >>
> >>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >>
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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On Thu, Feb 01, 2018 at 04:47:03PM -0500, James Y Knight via llvm-dev
wrote:
> That said, I do think it could make sense to prepare llvm for the world in
> which "python" is python3 on some systems. So, I'd propose
the following:
> 1. Change all #! lines to say "#!/usr/bin/env python2.7" instead
of "#!/usr/bin
> /env python", if they only work with 2.7.
> 2. If someone feels motivated, and if it doesn't make the code obtuse,
port
> scripts to work with either version -- and for such scripts, change the #!
line
> to say "#!/usr/bin/env python".

I've started the work:

    https://reviews.llvm.org/D55121

More patch may come if there's an interest in that.

On Fri, Nov 30, 2018 at 03:25:10PM +0100, Serge Guelton via llvm-dev
wrote:
> On Thu, Feb 01, 2018 at 04:47:03PM -0500, James Y Knight via llvm-dev
wrote:
> > That said, I do think it could make sense to prepare llvm for the
world in
> > which "python" is python3 on some systems. So, I'd
propose the following:
> > 1. Change all #! lines to say "#!/usr/bin/env python2.7"
instead of "#!/usr/bin
> > /env python", if they only work with 2.7.
> > 2. If someone feels motivated, and if it doesn't make the code
obtuse, port
> > scripts to work with either version -- and for such scripts, change
the #! line
> > to say "#!/usr/bin/env python".
> 
> 
> I've started the work:
> 
>     https://reviews.llvm.org/D55121
> 
> More patch may come if there's an interest in that.
Most if not all Python scripts in the clang/ repo have been ported and are
waiting for reviews.
I've split them in independant patches to ease the review works:

https://reviews.llvm.org/D55259
https://reviews.llvm.org/D55258
https://reviews.llvm.org/D55213
https://reviews.llvm.org/D55208
https://reviews.llvm.org/D55205
https://reviews.llvm.org/D55204
https://reviews.llvm.org/D55202
https://reviews.llvm.org/D55200
https://reviews.llvm.org/D55199
https://reviews.llvm.org/D55197
https://reviews.llvm.org/D55196
https://reviews.llvm.org/D55193
https://reviews.llvm.org/D55194

Have fun with these!